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Ambipolar to Unipolar Conversion in C70/Ferrocene Nanosheet Field-Effect Transistors.
Dorra Mahdaoui1,2, Chika Hirata1, Kahori Nagaoka1
1Electronic Functional Macromolecules Group, Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Ibaraki, Japan.
Organic cocrystals of C70/ferrocene (Fc) exhibit ambipolar charge transfer (CT) properties. Upon heating, Fc elimination transforms them into thermally stable, n-type semiconductors, showcasing tunable electronic behavior.
Area of Science:
- Materials Science
- Organic Electronics
- Supramolecular Chemistry
Background:
- Organic cocrystals assembled via noncovalent interactions offer unique properties.
- Charge transfer (CT) interactions in cocrystals are key to their semiconductor characteristics.
- C70/ferrocene (Fc) cocrystals are explored for their potential in electronic devices.
Purpose of the Study:
- To investigate the ambipolar charge transfer (CT) properties of C70/Fc single cocrystal nanosheets.
- To explore the effect of thermal treatment on the crystal structure and semiconducting behavior of C70/Fc nanosheets.
- To compare the thermal stability of C70/Fc nanosheet-based field-effect transistors (FETs) with related C60/Fc systems.
Main Methods:
- Fabrication of C70/Fc single cocrystal nanosheet-based field-effect transistors (FETs).
- Thermal annealing at 150 °C to induce structural and electronic changes.
- Visible/near-infrared diffuse reflectance and photoemission yield spectroscopies to analyze CT characteristics.
Main Results:
- Initially ambipolar C70/Fc nanosheet FETs transformed into n-type C70 nanosheet FETs after heating, due to Fc elimination.
- This thermal treatment caused an irreversible transition from ambipolar to unipolar semiconducting behavior.
- C70/Fc nanosheet FETs demonstrated enhanced thermal stability compared to previously reported C60/Fc counterparts.
Conclusions:
- The study highlights the tunable, thermally switchable semiconducting behavior of C70/Fc cocrystal nanosheets.
- Ferrocene plays a crucial role in modulating the charge transfer characteristics and initial ambipolarity.
- These findings offer valuable insights into the design and functionality of organic cocrystal-based electronic devices.
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